package cn.zust.ly.ExExample.Ex02;

import java.util.Scanner;

/**
 * Created by liy on 2016/11/14.
 */
public class Main {

    static double PI = 3.14159265358979323;

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while (true) {
            int r = sc.nextInt();
            double s = PI*r*r;
            //System.out.printf("%.7f",s);
        }

    }

}
